21372197 has 16 divisors (see below), whose sum is σ = 27153792. Its totient is φ = 16336320.

The previous prime is 21372187. The next prime is 21372227. The reversal of 21372197 is 79127312.

It is not a de Polignac number, because 21372197 - 2⁴ = 21372181 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21372157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1463 + ... + 6699.

It is an arithmetic number, because the mean of its divisors is an integer number (1697112).

Almost surely, 2^21372197 is an apocalyptic number.

It is an amenable number.

21372197 is a deficient number, since it is larger than the sum of its proper divisors (5781595).

21372197 is a wasteful number, since it uses less digits than its factorization.

21372197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5308.

The product of its digits is 5292, while the sum is 32.

The square root of 21372197 is about 4623.0073545258. The cubic root of 21372197 is about 277.5128235829.

It can be divided in two parts, 2137 and 2197, that added together give a palindrome (4334).

The spelling of 21372197 in words is "twenty-one million, three hundred seventy-two thousand, one hundred ninety-seven".